LAS VEGAS — Leaving behind the chaos he sowed in Washington with his shifting immigration policies, President Trump visited his second midterm battleground state of the week on Saturday to deliver the blunt message he has repeated at rallies for weeks: “We need more Republicans.”

For a few hours, at least, Mr. Trump put the intricacies of governing in his rearview mirror, attending a Republican convention on the outskirts of the city here, a private event for Senator Dean Heller and a tax-focused round-table discussion.

Back in the capital, some government officials are reeling over directives toenforce — and, as of Wednesday, reverse — Trump administration policies that resulted in the separation of some 2,300 children from their parents at the border. Congressional Republicans, stalled by dysfunction and flummoxed by the president’s back-and-forth orders, are unsure how to proceed with a legislative fix before November.

Mr. Trump, seemingly unconcerned by the clashes, has instead focused on deploying an old campaign tactic: inundating the public with conflicting messages, then hitting the trail to speak to supporters who are more focused on winning the state and sharing his grievances about the Democrats.

“‘Let’s leave North Korea for Trump,’” Mr. Trump lamented, referring to the Democrats during a 45-minute speech that echoed his stop on Wednesday in Duluth, Minn. “‘Let’s leave trade for Trump. Let’s leave immigration for Trump.’ They left us a lot, but I’m actually having a good time.”

Mr. Trump was here to stump for Mr. Heller, a Republican whose seat is widely seen as the best chance of a Democratic pickup. Mr. Heller, 58, is in a politically precarious position after having first angered Republicans by voting against the repeal of the Affordable Care Act, then angering Democrats by voting for a modified version of a repeal.

Mr. Heller’s race against Representative Jacky Rosen, a Democrat, will be one of the most competitive in the country this fall. In Reno on Saturday, about 400 miles from Mr. Trump’s events, Ms. Rosen spoke at a Democratic convention, held in a cavernous casino ballroom, and made it clear that Mr. Heller should pay a price for his decision to align himself so closely with the president.

“Senator Heller, he had a clear choice on health care: listen to Nevadans, or listen to Mitch McConnell and Donald Trump,” Ms. Rosen said. “He broke his promise. He broke his promise to all Nevadans.”

In the keynote speech, Senator Elizabeth Warren, Democrat of Massachusetts and a potential presidential candidate, railed against Mr. Trump and seemed to hint at a 2020 run. Politics needed more women in power, she said, including in “that really nice oval-shaped room at 1600 Pennsylvania Avenue.”

Ms. Warren assailed the administration as “corrupt” and took aim at Mr. Trump’s hard-line immigration policies. “That’s what Donald Trump and his Republican enablers in Congress stand for: hatefulness, ugliness, cruelty,” she said.

And Ms. Rosen, invoking the “immoral” separation and detention of migrant families at the southern border, called on Mr. Heller to pressure Mr. Trump to resolve the crisis there. “He should have the backbone to personally ask the president — talk to the president today, at their fund-raiser,” Ms. Rosen said. “We need a real solution.”

Mr. Trump responded by name-calling and lobbing a racially charged epithet at Ms. Warren that he has used in the past to mock her account of having Native American ancestry. “Wacky Jacky is in Nevada right now campaigning with Pocahontas,” he said.

Nearby, Mr. Heller received tepid applause whenever the president mentioned him. This month, Mr. Heller was among 13 Senate Republicans who publicly opposed the administration’s family separation policy. But if that came up on Saturday in his private meeting with the president, he did not address it. Instead, he praised Mr. Trump as “the most powerful man in the world,” and emphasized the need to keep tax cuts in place.

The president was not the only visitor to receive a hero’s welcome. Corey Lewandowski, Mr. Trump’s former campaign manager, posed for selfies and shook hands with supporters, days after reacting to stories of separated families with a blustering “womp womp” during a TV interview. That televised defense earned him a spot on Air Force One for the trip.

With his defenders in tow, Mr. Trump offered rebuttals to Democrats and the news media that seemed more fitting of a subdued casino convention attended by delegates in a razor-thin swing state than a raucous campaign rally attended by red-meat supporters.

He left his promises about immigration forceful but vague, declining to mention misleading statistics about immigrant crime in the United States, as he did in a speech on Friday.

“Our issue is strong borders, no crime,” Mr. Trump said on Saturday, invoking the MS-13 gang and a “tremendous” flow of violence into the country by immigrants. (Studies have found that immigration has no effect on crime, and that crime has actually decreased despite the increasing immigrant population.)

“Their issue is open borders,” Mr. Trump said of the Democrats.

He also updated the crowd with progress on his plans for the border wall, which drew a round of “build the wall” chants.

“We’re going to build the wall and we started it,” Mr. Trump said. “We’re going now for our second portion.”

That is misleading: While prototypes for the new border wall were unveiled in late October, construction has not yet begun on the 1,000-mile border wall. The Border Patrol has instead started replacing old barriers with new barriers.

Mr. Trump also seemed to take issue with coverage in this newspaper over his diplomatic efforts with North Korea. He again repeated a few misleading claims that overstate the efforts by North Korea’s leader, Kim Jong-un, to dismantle his nuclear arsenal.

“We have a great chemistry together,” Mr. Trump said of Mr. Kim.

Mr. Kim has said he will take steps to denuclearize the Korean Peninsula but has not begun to dismantle his arsenal of nuclear weapons. Analysts who study the country say it would be premature to declare progress until that happens.

Still, Republicans in the crowd applauded, giving several standing ovations during the speech. Mendy Elliot, a consultant, was one of them.

“It really reaffirms the importance of that Senate seat,” Ms. Elliot said, “not only in Nevada but to the administration. What’s at risk is his agenda.”

Before leaving for a second round-table discussion geared toward tax overhaul, Mr. Trump said visiting Nevada would be a focus for him before the midterms.

A version of this article appears in print on , on Page A26 of the New York edition with the headline: Leaving Legislative Chaos Behind, Trump Stumps for Nevada Senator. Order Reprints | Today’s Paper | Subscribe